frontend: fix full_page extensions not showing up #2905

Job	Run time
frontend-tests	2m 22s
python-tests	3m 36s
deploy-docker-images (bootstrap, blueos, linux/arm/v7,linux/arm64/v8,linux/amd64)	5m 12s
deploy-docker-images (core, blueos, linux/arm/v7,linux/arm64/v8,linux/amd64)	10m 25s
deploy-raspberry-image	0s
	21m 35s

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